Ec25 eg25-g sim registration denied

i am using sixfab ec25 eg25-g with the sixfab sim and the registration is being failed.
the AT+CREG? is returning 0,3. What is causing this issue?
Some outputs are shown below.

pi@raspberrypi:~ $ atcom AT+CREG?

+CREG: 0,3

OK

pi@raspberrypi:~ $ atcom AT+CPIN?

+CPIN: READY

OK

pi@raspberrypi:~ $ atcom AT+CSQ

+CSQ: 22,99

OK

pi@raspberrypi:~ $ atcom AT+CGDCONT?
AT+CGDCONT?
+CGDCONT: 1,“IPV4V6”,“super”,“0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0”,0,0,0,0
+CGDCONT: 2,“IPV4V6”,“ims”,“0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0”,0,0,0,0
+CGDCONT: 3,“IPV4V6”,“”,“0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0”,0,0,0,1

OK

pi@raspberrypi:~ $ atcom AT+QCFG="usbnet"

+QCFG: “usbnet”,1

OK

pi@raspberrypi:~ $ atcom AT+CGCONTRDP

+CREG: 0,3

OK